土壤碳循环研究进展

土壤碳是陆地碳库的主要组成部分,全球土壤有机碳总量达1270 Gt。气候变化影响植物生长、植物碎屑分解速率以及土壤—大气碳通量,这对大气CO₂含量有重要影响。土壤有机质模型是研究生态系统尺度土壤碳循环的唯一可用工具,目前已开发出多种。大量研究表明,¹⁴Ｃ测试是研究土壤有机碳组成及驻留时间的重要手段,土壤有机碳由一系列具不同更新时间的组分构成。土壤粒级组成、矿物特征及土体结构等内在因素制约土壤有机碳存量及状态,对于长时间尺度碳的更新具有重要意义。研究不同气候带土壤有机碳储量及动态变化特征,可为预测未来农、林生态系统变化提供理论依据。     

结构—功能—生境框架下的西南喀斯特生态系统脆弱性研究进展

特殊的地质背景与生态环境叠加强烈的人类活动,导致中国西南喀斯特地区生态系统呈现显著的脆弱性特征。从生态系统敏感性和适应性角度出发,喀斯特生态系统结构、功能和生境对外界扰动响应的脆弱性特征研究已取得一定进展,尤其是借助物种多样性、生态系统生产力、土壤水分/养分等指标揭示了喀斯特生态系统对土地利用/覆被变化、石漠化等过程的敏感性等方面,但综合野外试验、数值模拟、数理统计等手段的生态系统敏感性定量化研究仍较薄弱。在生态系统适应性方面,虽然具有喜钙、耐旱以及石生等特性的植物种群通过形态结构和生理功能的自我调节能够呈现出对岩溶环境的适应性,但喀斯特生态系统对人类干扰和气候变化等环境胁迫响应的适应机制仍缺乏长期的生物及理化过程研究。今后,应针对生态系统结构、功能、生境间的正反馈机制,增强系统组分的耦合分析,加强喀斯特生态系统脆弱性驱动机制研究与定量评估,突出系统脆弱性在石漠化遏制和生态恢复重建中的关键地位。     

基于生态系统服务视角的“土地分离与共享框架”解析

“土地分离和共享框架”是协调物质生产和生态保护、促进土地可持续利用的重要理论。本文梳理了“土地分离与共享框架”和生态系统服务间关联,剖析生态系统服务应用于该框架的理论基础,结合美国典型土地共享案例,分析了土地利用策略选择对粮食生产、生物多样性、直接和间接生态系统服务的影响,并探讨了该框架对中国生态系统工程的启示。结果表明：随着人类对土地功能认知的不断深入,“土地分离与共享框架”的拓展表现为从单一的粮食供给服务需求演进到粮食供给服务和其他生态系统服务的综合需求。当粮食供给服务与其他服务处于权衡状态时,在生态脆弱、恢复力差的地区,不同生态系统服务间多处于凸权衡关系,一般适宜采用分离策略;在生态系统稳定、恢复力强的地区,不同生态系统服务多处于凹权衡关系,一般适宜采用共享策略。结合美国典型土地共享案例发现,其土地利用实践中选择土地功能共享策略是比较适宜的;生态系统服务作为政策评估工具,可在策略选择和评估实施效果中发挥一定作用。研究结果可为可持续土地利用提供理论与方法支撑,并为中国制定土地利用策略提供参考。     

山地区域土地生态红线划定方法与实证研究——以重庆市涪陵区义和镇为例

无序和不合理的土地利用是引发生态问题的重要因素。合理划定土地生态红线,可协调土地利用和生态环境的关系,促进土地资源的合理配置,保障区域生态安全。山地区域地势起伏较大,水系密布,土地利用破碎化,作为重要的水土保持和水源涵养区域,是进行生态恢复和重建的关键地区。本文以山地区域村镇为例,运用GIS平台,基于生态敏感性和生态服务价值,对土地生态进行综合评价,据此划定刚性和弹性的土地生态红线。生态敏感性评价的指标包括坡度、植被覆盖度、水体、土壤类型和降水侵蚀力等5个指标;生态服务价值评价的指标包括食物生产、原料生产、气体调节、气候调节、水文调节、土壤保持、维持养分循环、生物多样性和美学景观9个指标。义和镇的刚性生态红线内所包含的刚性生态保护区面积为43.90 km²,占义和镇总面积的44.34%。弹性生态红线包含的弹性生态保护区面积为29.18 km²,占义和镇总面积的29.47%。义和镇的生态红线范围主要包含东北部山地区域和南部水系丰富地区,该区域的生态敏感性较高,同时也有较高的生态服务价值,因此生态红线的划定对于生态修复和生态保护具有指引作用,为生态系统健康发展提供基础保障,并可为构建生态文明安全格局提供科学支持。     

中国工业化、城镇化、农业现代化、信息化、绿色化“五化”协调定量评价的进展与反思

工业化、城镇化、农业现代化、信息化、绿色化“五化”是社会现代化战略的重要支撑。“五化”协调定量评价是近年来一个研究热点。本文通过梳理和总结国内关于“五化”协调发展定量研究发现：①“五化”协调发展的内涵解读不一,评价时往往选择单指标,与综合指标差异很大。②权重计算以熵权法为主,层次分析法等主观评价方法较少,主客观评价结合更少。③协调水平的研究方法主要以耦合度、耦合协调度为主,其次为关系拟合与趋势预测法、DEA动态效率+HR模型、同步度模型等,并出现了系统性研究方法以及多种方法的交叉,研究方法的层次不断提高。④空间分析方法以空间分类与探索性空间数据分析为主,空间重心转移轨迹、空间格局的动态演进、空间趋势分析等研究方法逐渐出现。⑤时空分异的机理分析主要以影响因子解读与多元线性回归模型为主,空间滞后模型(SLM)、空间误差模型(SEM)、地理加权回归模型(GWR)等考虑空间因素的回归模型开始出现。但“化”的过程性、阶段性分析不足,“化”与“化”协调发展的转折点及转型机制分析不足。根据研究进展的评析,从研究范式、指标选择与权重计算、研究方法、空间分析技术、时空分异的机理解释等方面进行了反思,提出了加强“五化”协调发展的内在机理与评价维度分析、加强指标体系构建和权重设置的合理性研究、采用多元的“五化”协调度评价方法、加强空间分析技术的综合应用、促进定量解释与定性解释的结合等建议。     

基于LUCC的张家界市生态补偿研究

本文基于张家界市土地利用/土地覆盖变化,通过改进的生态系统服务价值与生态足迹的方法,测算了研究区域的生态补偿额度。研究表明:(1)从2001~2013年张家界市各县(区)生态系统服务价值变化率来看,永定区呈下降态势;增幅最大的是武陵源区,其次是桑植县,慈利县增幅最小。(2)2013年张家界市的人均生态足迹为1.3625 hm~2,而实际生态承载力为0.9556 hm~2,人均可利用生态承载力为0.8409 hm~2,则人均生态赤字为-0.5215 hm~2。(3)计算出了张家界市各县(区)的生态补偿标准,其中慈利县需要支付的生态补偿量最高,为18.61亿元;其次是永定区,为10.49亿元;再次是武陵源区,为582.12万元;最小的是桑植县,为359.70万元。评价结果将促进张家界市生态环境保护和经济社会的可持续发展。     

Integrating agriculture and energy to assess GHG emissions reduction: a methodological approach

Agriculture is responsible for approximately 25% of anthropogenic global GHG emissions. This significant share highlights the fundamental importance of the agricultural sector in the global GHG emissions reduction challenge. This article develops and tests a methodology for the integration of agricultural and energy systems modelling. The goal of the research is to extend an energy systems modelling approach to agriculture in order to provide richer insights into the dynamics and interactions between the two (e.g. in competition for land-use). We build Agri-TIMES, an agricultural systems module using the TIMES energy systems modelling framework, to model the effect of livestock emissions and explore emissions reduction options. The research focuses on Ireland, which is an interesting test case for two reasons: first, agriculture currently accounts for about 30% of Ireland's GHG emissions, significantly higher than other industrialized countries yet comparable with global levels (here including emissions associated with other land-use change and forestation); second, Ireland is both a complete and reasonably sized agricultural system to act as a test case for this new approach. This article describes the methodology used, the data requirements, and technical assumptions made to facilitate the modelling. It also presents results to illustrate the approach and provide associated initial insights.

Policy relevance

Most of the policy focus with regard to climate mitigation targets has been on reducing energy-related CO₂ emissions, which is understandable as they represent by far the largest source of emissions. Non-energy-related GHG emissions – largely from agriculture, industrial processes, and waste – have received significantly less attention in policy discourse. Going forward, however, if significant cuts are made in energy-related CO₂ emissions, the role of non-energy-related GHG emissions will grow in importance. It is therefore crucial that climate mitigation analyses and strategies are not limited to the energy system. This article shows the value of using integrated energy and agriculture techno-economic modelling techniques to draw evidence for new comprehensive climate policy strategies able to discern between the full range of technical solutions available. It enables the production of economy-wide least-cost climate mitigation pathways.     

Diversity of faunal assemblages associated with ribbed mussel beds along the South American coast: relative roles of biogeography and bioengineering

Benthic organisms are among the most diverse and abundant in the marine realm, and some species are a key factor in studies related to bioengineering. However, their importance has not been well noted in biogeographic studies. Macrofaunal assemblages associated with subtidal beds of the ribbed mussel (Aulacomya atra) along South America were studied to assess the relationship between their diversity patterns and the proposed biogeographic provinces in the Southeastern Pacific and Southwestern Atlantic Oceans. Samples from ribbed mussel beds were obtained from 10 sites distributed from the Peruvian coast (17°S) to the Argentinean coast (41°S). The sampling included eight beds in the Pacific and two in the Atlantic and the collections were carried out using five 0.04 m² quadrants per site. Faunal assemblages were assessed through classification analyses using binary and log‐transformed abundance data. Variation in the size and density of mussels, and in the species richness, abundance and structure of their faunal assemblages were tested using a permutational multivariate analysis of variance. Faunal assemblages showed a north–south latitudinal gradient along both the Pacific and Atlantic coasts. Binary and abundance data showed a difference in the resulting clustering arrangement of Pacific sites between 40°S and 44°S, indicating a pattern of continuity in the species distribution associated with biological substrates. At a regional scale, the distribution of species along the South American coast matched the general provincial pattern shown by prior studies, which show two biogeographic units on the Pacific coast separated by an intermediate (probably transitional) zone and a single province on the Atlantic coast extending up to Northern Argentina. Biological substrates such as ribbed mussel beds play an important ecological role by making a similar habitat type available on a large scale for a variety of invertebrate species. Despite such habitat homogeneity, however, the associated fauna exhibit marked distribution breaks, suggesting strong constraints on dispersal. This therefore suggests that macrofaunal assemblages could possibly be used as biogeographic indicators.     

A model to assess fundamental and realized carrying capacities of island ecosystem: A case study in the southern Miaodao Archipelago of China

Research on carrying capacity, aiming at maintaining the limited ability of the Earth's life supporting system to sustain human development, requires a comprehensive and ecosystem-based approach to monitor and assess the localized sustainability of coupled social and ecological systems. A definition termed the ecosystem-based carrying capacity of island (EBCCI) was developed in this paper of which the indices of fundamental and realized carrying capacities of island (FCCI and RCCI) were highlighted to emphasize the inter-dependencies between social systems and ecological systems. In order to avoid the difficulties and uncertainties of direct assessment, the related assessment model was established on the basis of synthetic evaluation of inherent and external factors affecting the EBCCI. The southern Miaodao Archipelago (SMA) located in the intersection of the Bohai Sea and the Yellow Sea, China, was taken as a typical example to acquire integrated recognition of the island ecosystem and its carrying capacity so as to discuss its sustainable development. The index scores of FCCI and RCCI in the SMA were 0.818 5 and 0.712 9 out of 1.0, respectively, with acceptable uncertainties. The results showed a relatively well capacity to sustain progress and relatively well realization of the carrying capacity of island ecosystem, owing to a well capacity of ecologically regulating, general performance of both ecologically supporting and resource provisioning, and a relatively high level of social supporting system. The study implied that it was critical to optimize the inter-dependencies and to sustain the relative balance between social systems and ecological systems so as to improve the RCCI and further facilitate the sustainability of SMA. The approach proposed in this paper provides a powerful tool which is well applicative to the regional level of an oceanic island or archipelago to study the sustainable development and can be further popularized to the coastal zone.     

基于河口潮间带底栖微藻群落水平的环境质量状态评价

The feasibility of community-based bioassessment of environmental quality status was studied using microphytobenthos(MPB) in estuarine intertidal ecosystems.The sediment samples of MPB were collected monthly during a 1-year cycle(September 2006–August 2007) at four sampling stations in the Nakdong River Estuary,Korea.Environmental variables,such as salinity,radiation,grain size of sediment,Si(OH)_4(Si),nitrate(NO_3~–),nitrite(NO_2~–),ammonium(NH_4~+) and phosphates(PO_4~(3–)),were measured synchronously for comparison with biotic parameters.The statistical analyses were carried out for assessment the relationship between biotic and environmental parameters.The results showed that:(1) the MPB community structures were significant differences among four sampling stations;(2) spatial variation in the MPB communities were significantly correlated with environmental variables,especially the nutrient NH_4+ in combination with salinity and grain size;(3) three species(Navicula lacustris,Pleurosigma anglulatum and Fragilaria sp.1) were significantly correlated with nutrients and/or Si;and(4) the species richness and diversity were significantly correlated with the grain size.It is suggested that MPB communities may be used as a potentially robust bioindicator for assessing environmental quality status in estuarine intertidal ecosystems.